As a plumber subcontractor, you are hired by a contractor to provide various plumbing services. Your duties may involve installing pipes for new building construction, assisting with a particularly large project, or verifying the fittings after another job is finished. Many details of this job depend on the plumber you subcontract for. For example, some clients may ask you to take on various smaller jobs so they can focus on large jobs, while others may ask you to step in as needed when they require extra help. In this role, you often interact with customers and may need to respond to emergency calls.